Strand treatment

ABSTRACT

TEXTILE STRANDS ARE SUBJECTED TO SUCCESSIVE COMPRESSIVE CRIMPING STEPS, AS IN SUCCESSIVE STUFFER CRIMPERS, AT ESSENTIALLY CONSTANT, THOUGH DIFFERENT, INFEED AND WITHDRAWAL OR WINDUP RATES. CONTROL TENSION IS APPLIED BETWEEN SUCH SUCCESSIVE STEPS AND OPTIONALLY AFTER THE LAST SUCH STEP.

March 16, 1971 R. K. STANLEY ETAL- 3,570,084

v STRAND TREATMENT Filed April 11, 1969 2 Sheets-Sheet l ROBERT K.STANLEY MALCOLM F. IRVHN March 16, 1971 R. K. STANLEY El'AL 3,570,084

STRAND TREATMENT Filed April 11, 1969 2 Sheets-Sheet 2 72,2 I O O l 7 II J 27! //a V L i m mvmxu 1 1 ROBERT K. STANLEY MALCOLM F. IRWIN 7% wUnited States Patent Int. Cl. D02g 1/12 US. Cl. 28-7214 15 ClaimsABSTRACT OF THE DISCLOSURE Textile strands are subjected to successivecompressive crimping steps, as in successive stuffer crimpers, atessentially constant, though difierent, infeed and withdrawal or winduprates. Control tension is applied between such successive steps andoptionally after the last such step.

This application is a continuation-in-part of my c0- pending applicationSer. No. 688,119 filed Dec. 5, 1967 and now Pat. 3,500,518. Reference isalso made to my US. Pats. 3,386,142 and 3,279,025 granted for relatedsubject matter and the contents of which, insofar as pertinent hereto,are incorporated herein by reference.

It is conventional to crimp a textile strand compressively by feeding itby suitable means, such as between a pair of nip rolls, into theentrance of a temporarily confining region, in which the strandaccumulates under pressure for some time before exiting therefrom andupon entering is compressed longitudinally to buckle into a modifiedzigzag or sawtooth crimped configuration. Multiple crimping of strandsby application of successive crimping steps thereto is known butregardless of crimping method is complicated by apparent necessity forsynchronization of the strand infeed rate and withdrawal or windup rateby varying such rate or rates.

A primary object of the present invention is fixed-speed crimping of atextile strand in successive crimping steps.

Another object is multiple stutter-crimping of textile strands insuccessive crimping steps.

A further object is improved stabilization of crimp in crimped textilestrands by application of successive crimping steps thereto.

Other objects of this invention, together with means and methods forattaining the various objects, will be apparent from the followingdescription and the accompanying diagrams.

FIG. 1 is a schematic representation of the processing of a textilestrand through a first stutfer-crimping step according to the presentinvention;

FIG. 2 is a front elevation, partly cut away, of component apparatus ofthe preceding view, with strand shown passing therethrough;

FIG. 3 is a side elevation of the apparatus and strand of FIG. 2;

FIG. 4 is a plan of the apparatus of FIGS. 2 and 3;

FIG. 5 is a schematic representation of a succeeding stuffer-crimpingstep according to this invention;

FIG. 6 is a front elevation, partly cut away, of component apparatus ofthe preceding view, with strand shown passing therethrough;

FIG. 7 is a side elevation of the apparatus and strand of FIG. 6; and

FIG. 8 is a plan of the apparatus of FIGS. 5 and 7. 6

In general, the objects of the present invention are accomplished, insuccessive crimping of a textile strand wherein the strand is withdrawncontinuously at an essen tially constant rate from a first crimping zoneand is fed continuously at an essentially constant rate into asucceeding crimping zone. In a preferred embodiment of this invention,both such zones are stulfer-crimping zones. According thereto,additional tension is imposed on the strand between the withdrawalthereof from the first crimping zone and the entry thereof into theimmediately succeeding crimping zone, such tension being essentiallyconstant but adjustable.

Such added tension is used to control degree or extent of crimp atconstant withdrawal and constant feed rates of the strand from onecrimping zone to the next, which is astonishing because it would beexpected that unless the withdrawal and feed rates were the same or atleast were set at a particular fixed ratio to one another, the strandwould either break or overflow between the successive crimping zones. Itwill be apparent that adjustment of the tension from one value toanother is considerably simpler and more efficient than adjustment ofeither rate, and such control facility is a principal benefit of thisinvention.

FIG. 1 shows, schematically, strand 10 unwinding from conical package 11to pass through guide 12 and successive pairs of rolls 13, 13' and 15,15, with heater 14 for the strand intervening between the respectivepairs of rolls. Strand-traversing means 16 precedes pair of nip rolls17, 17 which feed the strand into stufiing chamber 18, normally at afixed or constant rate. Part of the chamber is cut away to revealtherein strand accumulation 10a, from which crimped strand designated as10' is withdrawn longitudinally upward. After being withdrawn from theexit of the chamber and through tensioning means 19, the crimped strandis then denoted as 10", at least until reaching the next treatinglocation.

The stufling chamber, feed rolls, and related stufiercrimping componentsare shown in greater detail, together with components of the tensioningmeans in subsequent views. Drive means for the stuifer-crimper feedrolls are shown in some detail to aid understanding thereof. It will beunderstood that such drive means preferably include adjustableconstant-speed electrical or mechanical devices, which may be andpreferably are wholly conventional in design and, therefore, not shown.Nor is there any showing of drive means for the other rolls, both forthe same reason of conventionality and also because some of them neednot be driven at all, as is well known.

FIGS. 2, 3, and 4 show the indicated components and associated elementsof the same apparatus in front and side elevation and plan,respectively. Part of chamber 18 is cut away in FIG. 2. to revealcrimped strand 10 and accumulation 10a thereof in bore 28 of thechamber, which is shown in the shape of a square cylinder. Strand 10after passing between nip rolls 15, 15 passes through strand-traversingmeans 16 and into the nip of feed rolls 17, 17'. The latter rolls feedor stuff the strand into the entrance to the bore of the chamber, thefront and rear walls of the chamber overlapping the front and rear facesof the rolls as far as the nip so as to ensure that all the strandenters the chamber. As the strand accumulates in the chamber, theentering strand meets with resistance provided by the previouslyaccumulated strand and buckles back and forth upon itself into amodified sawtooth or zigzag configuration or crimp. As more strand isfed continuously into the chamber the compact strand accumulation isforced along through the bore toward the exit therefrom.

Chamber 18, into which the strand is stuffed and in which it assumescrimped configuration, is supported on the front wall of frame 22, whichhas an inverted U-shape in side elevation. Shafts 27, 27' for respectivefeed rolls 17, 17 are journaled in the front and rear walls of the frameand have intermeshing gears 37, 37 thereon behind the rear wall of theframe. Shaft 27' also has pulley 29 thereon. Motor 31 on the horizontalupper surface of the frame has shaft 32 on which is pulley 33. Belt 34interconnects pulleys 33 and 29 to transmit rotational force to thegears, shafts, and the feed rolls themselves. The direction of rotationis such as to feed or stuff the strand by and between thecounter-rotating feed rolls into the entrance of the chamber. As alreadyindicated, the infeed rate is normally constant, although it may beadjustable to different rates to accommodate different strands orchanges in operating conditions.

The exit end of the chamber bore, located at the same level as theentrance in the embodiment shown in FIG. 1 and at a level verticallyabove the level of the entrance in the embodiment (which may beotherwise the same) shown in FIGS. 2, 3, and 4, is shown unobstructed,as is the rest of the bore. Crimped strand denoted as is withdrawn at aconstant or fixed rate, which may be adjustable if desired, from strandaccumulation 10a inside and is passed through tensioning means 19,discussed in detail below. Thereafter the strand, then denoted as 10",is withdrawn to a succeeding crimping zone, also described hereinafter.

Tensioning means 19, a preferred embodiment of which is shown in detailin FIGS. 2 and 3, comprises several rolls rotatably mounted on asupporting framework and means for retarding rotation of the rolls so asto superimpose tension on strand 10 passing thereover. Framework 40 hasat one side vertical flange 50 extending downward alongside stuffingchamber 18 and adjacent lateral extension 18a thereof to frame 22 towhich it is affixed. Supported on the framework, first roll 41 on axle41a and third roll 43 on axle 43a are both contiguous with minorcylindrical portion 42 of second roll 42, which is mounted on axle 42aparallel to the other two axles. The first and third rolls do not touchone another. Strand 10 passes about slightly less than half of each ofthe first and third rolls and about three-fourths of the minor portionof the second or intermediate roll, passing between the nip formed byeach of the first and third rolls with the latter, after which thestrand is denoted as 10". Belt or strap 52 extends about a quadrant ofthe major portion of roll 12 from a fixed location on flange 50 at oneend to stop 53 at the other end, upon which are supported weights 54,thereby biasing the belt or strap into frictional contact with the rollsurface.

Strand 10' is pulled, as by the feed means of a succeeding stuffercrimper shown in subsequent views (or by forwarding rolls, etc.), inessentially non-slipping contact with first roll 41, minor portion 42'of the second roll, and third roll 43, thereby rotating them in thedirections indicated by the arrows. The major portion of roll 42 rotatesin slipping frictional contact with belt or strap 52, which counters thepositive rotation and thereby tensions the strand. The tension can beincreased by adding weights, and be reduced by subtracting weights,carried by the belt or strap. Suitable tensions for nylon strands ofabout 2000 total denier and 140 filaments are on the order of tenths ofa gram per denier, depending upon the desired degree of crimp, half agram per denier often being a satisfactory value. The resulting tensionin the strand is essentially constant at a maximum value determined bythe frictional contact just described, which tends to smooth outpreexisting tension irregularities in the strand. As the control ispassive, rather than active, it cannot superimpose additional tensionvariations upon the strand.

Adjustment is simplicity itself, and maintenance is practically nil.

When the described stuffer crimper is being started up, it is desirableto insert a rod or the like in the open end of chamber 18 to compressthe first bit of strand being fed therein until a wad of crimped strandhas accumulated, after which the accumulated strand may be allowed to beforced further in the chamber from the entering end, accumulatingadditioinal strand in crimped configuration behind it. Contrary to priorpractice, no added means is necessary to apply crimping back pressure tothe strand during operation of the apparatus of this invention, althoughsome could be used at or upstream from the furthermost downstreamlocation of the compact accumulation of crimped strand, if desired, butpredictably with less beneficial effect. Despite the lack of physicalobstruction of the chamber the apparatus may be operated with thechamber in any desired orientation: e.g., horizontal as in FIG. 1,upright as in succeeding views, or at any intermediate angle, and eveninverted (not shown).

Heater 14 optionally heats the strand to desirable crimping temperature(e.g., 150-350 F.), and the stuffing chamber may be heated as well, suchas by a heating jacket or by resistance coils in the chamber wall(neither shown) to preclude cooling or excessive cooling of the strandin the chamber, although it normally will be at an appreciably lowertemperature at the exit (e.g., about 120 F.) than at the entrance of thechamber. Any suitable means may be used to preheat the strand, such ashot rolls, a bar type of heater, etc., instead of the illustrated heatedchamber. Steam injection also may be used in either heater 14 or apreheating step. The actual heater temperature will depend upon thedegree of lubrication (if any) and rate of travel of the strand(1000-2000 yards or meters per minute is preferred) as Well as upon thestrand composition and denier, the chamber composition, and the methodof heating (conduction, convection, radiation, etc.). The stuffingchamber and other apparatus elements may be made of steel or otherdurable material. If desired, the inside wall of the chamber may becoated (e.g., with tetrafiuoroethylene) to reduce the coefiicient offriction, in which event the chamber should be lengthened accordingly. Achamber length of about a yard or meter (inner width about inch or acentimeter for use with strands of about 10 to denier) has provedsuitable for nylon and other commonly available textile strandmaterials, in an uncoated chamber.

As described, the strand is withdrawn from the accumulation in thechamber at a constant rate and under tension sufficient to keep thefurthest extent of the strand accumulation at some distance from the endof the cham ber, usually within the range of from about two-thirds toabout nine-tenths of the infeed rate. No means or method forsynchronizing windup and feed rates is required, as the crimped strandwill accumulate to a substantially constant level in the chamber, risingonly slightly thereabove and falling only slightly therebelow, thatlevel being determinable by setting the overall tension and, of course,by the physical characteristics of the strand, as well as thetemperature, wall friction, etc. Strand so crimped is free ofundesirable irregularities attributable to uneven application ofback-pressure by devices such as have been used in conventionalstuffer-crimping apparatus or to uneven application of heat to thestrand therein.

Preadjustment of the superimposed tension effects control of the degreeor extent of crimp in the strand, the tension and the crimp varying inthe same sense with respect to one another. Thus, a high tensionproduces an increased degree of crimp, together with a high level ofstrand in the chamber, as compared with a low level of strand anddecreased crimp at a lower tension. Degree of crimp may be determined byany conventional method, and high crimp may be apparent in part asincreased crimp frequency, reduced crimp leg length, reduced anglebetween adjacent legs, increased crimp retention under tension, or anycombination of these with one another, or possibly other crimpcharacteristics.

FIG. shows, schematically, further crimping of the strand whose crimpinghas been described above. In this and succeeding views, referencenumerals for items similar or corresponding to items treated in theforegoing description of previous views are higher by one hundred, andwith such indication in relationship specific mention of many thereof issuperfluous and is omitted below.

Output strand from the apparatus previously described and illustratedbecomes input strand 110 for the apparatus shown in FIGS. 5 to 8. Heater114 for the strand in advance of the entrance to this second crimpingapparatus is optional and may be useful for maintaining isothermalconditions rather than permitting the strand to cool between crimpingsteps to a temperature less than the temperature prevailing during thecrimping. In this respect the entire region from the entrance to theprevious crimper to the outlet from this crimper may be designed to meetthe requirements for the intermediate zone of my US. Pat. 3,348,283, theconents of which are incorporated herein by reference insofar aspertinent. Heater 114 preferably is of radiant electric, hot-airconvective, or other dry type, to avoid introducing or to help dispelundesired moisture as too close to windup of the product, whereasprevious heater 14 or an earlier preheater may utilize steam injection,as mentioned above.

Because of the crimp already imparted to the strand there is less reasonfor using means to traverse the strand with respect to feed rolls 117,117' at the entrance to stuffing chamber 118, although some suchtraversing means may be employed if desired. In other respects theapparatus and procedure are relatively unchanged, but after passingthrough tensioning means 119 resulting strand 110" is shown as beingwound onto cylindrical package 120 by grooved traversing drive roll 121.Alternatively the strand could be passed through another crimping zoneof the same or a different sort, if desired.

The two successive crimping steps with illustrated tension control,especially therebetween, provide a well stabilized crimped textilestrand having a lower potential shrinkage when subjected to furtherprocessing in conventional manner, thereby rectifying a feature (i.e.,relatively high shrinkage potential) of once crimped textile strandssometimes criticized. The resulting strands also are characterized bydesirable distribution of crimp about the longitudinal strand axis,whereas a single stuffercrimping often produces a more planar crimpdistribu tion instead. The resulting moisture content is more even,especially where the strand was subjected to one or more steps of steamheating or liquid application (e.g., finish in emulsion or dispersionform).

While operation at essentially adiabatic, or at leastconstant-temperature, conditions throughout is preferred, it will beapparent that this invention readily permits either a high-temperaturecrimping step followed by an otherwise similar low-temperature crimpingstep, or vice versa, either of which may be desired for whateverreasons.

Although a preferred embodiment of this invention has been illustratedand described, by way of example, modifications may be made thereinwhile retaining all or some of the advantages and benefits of theinvention. Minor restriction or impedance of the strand in its paththrough the temporarily confining region, preferably in the vicinity ofthe feed rolls rather than further downstream, may be employed ifdesired. Parts may be added, combined, rearranged, or subdivided andequivalents be substituted without departing from the invention asdefined in the following claims.

The claimed invention:

1. In crimping of a textile strand, the improvement com-prising crimpingthe strand in successive zones into and out of which the strand is fedand withdrawn at respective constant speeds, and controlling crimpingback pressure by superimposing tension thereon at the strand is betweenthe crimping zones.

2. The process improvement of claim 1, wherein the strand isstuffer-crimped in the successive zones.

3. The process improvement of claim 1, wherein the superimposed tensionis adjustable and is preadjusted to an essentially constant rate value.

4. The process improvement of claim 3 wherein the degree of crimp variesin accordance with the superimposed tension, and including the step ofpreadjusting the superimposed tension to a constant value at which apreselected degree of crimp is obtained in the strand.

5. The process improvement of claim 1, wherein the strand is heatedduring its passage between the successive zones.

6. The process improvement of claim 5, wherein the strand is maintainedat substantially constant temperature between the successive zones as inthe first of the zones.

7. The process improvement of claim 6, wherein the temperature of thestrand is maintained substantially constant throughout the successivezones.

8. Process comprising feeding a textile strand continuously at anessentially constant rate into a laterally confining region having anentrance and an exit, to accumulate temporarily therein in the form of acompressed strand accumulation being forced toward the exit byadditional strand fed thereagainst at the entrance to the region,controlling crimping back pressure and, thus, the degree of crimping bywithdrawing crimped strand from the accumulation thereof and out of theexit by application of forwarding tension thereto and superimposingadditional tension on the strand between the locus of withdrawal thereoffrom the strand accumulation and the forwarding location, and feedingthe strand into a like compressive crimping region at the forwardinglocation.

9. The process of claim 8, wherein the strand is preheated before beingfed into the first laterally confining region to accumulate temporarilytherein and is maintained at elevated temperature while in the confiningregion.

10. The process of claim 9, wherein the preheating comprises the step ofapplying steam to the strand.

11. The process of claim 10, wherein the strand is subjected to dryheating during its passage between the respective confining regions.

12. In stutter-crimping of a textile strand in a laterally confiningregion in which it accumulates temporarily under crimping compression,the improvement comprising reducing the shrinkage potential of thecrimped product by utilizing at least principally friction of lateralconfinement of the strand accumulation therein to apply crimpingback-pressure to the strand entering the region, removing strandtherefrom by withdrawing it from the leading edge of the strandaccumulation, adjusting to a desired constant value the tension on thestrand being withdrawn, including superimposing tension thereon inaddition to the tension required to withdraw the strand therefrom, andthereby controlling the amount of strand accumulation and theaccompanying crimping back pressure, forwarding the withdrawn strand atessentially constant forwarding rate greater than the withdrawal rate,and feeding the strand at essentially the forwarding rate directly to asucceeding stufier-crimping step.

13. The process improvement of claim 12, wherein essentially only thefriction of lateral confinement of the strand is utilized to applycrimping back-pressure to the strand in the laterally confining region,the strand accumulation being unconfined ahead thereof.

14. The process improvement of claim 12, wherein the strand is withdrawnfrom the succeeding stuifer-crimping step and is wound up therefrom at aconstant rate.

References Cited UNITED STATES PATENTS 1/1961 SWerdlOfi et a1 2872.144/1962 List et al. 28l.6

8 Ohashi et al 28l.6

Saito et a1. 287214 Stanley et a1 28l.6

Stanley 2872.14 Eskridge et a1. 2872.11

LOUIS K. RIMRODT, Primary Examiner

